The FAA currently allows pilots to log 14-hour workdays, which the NTSB says contributes to accidents.

The National Transportation Safety Board concluded in a report out Tuesday that pilot fatigue was a probable cause in a runway landing accident during bad weather in Michigan last winter. There were no fatalities.

The Federal Aviation Administration currently allows a 14-hour workday with eight hours of logged airtime.

"It's a critical issue; it's an insidious issue. Many times, the pilots themselves don't even recognize that they are fatigued when they get into that cockpit," NTSB Chairman Mark Rosenker said.

And Rosenker made the same points about air traffic controllers more than a year ago, in April 2007. In a letter to the FAA, Rosenker said that four other plane incidents "provide clear and compelling evidence" that controllers are sometimes operating while fatigued because of their work schedules and poor use of rest periods.

"That fatigue has contributed to controller errors," Rosenker wrote in 2007.

"Fourteen hours is still a very long day," NTSB board member Debbie Hersman said. Her conclusion is backed by 40 years of airline accident statistics compiled by the FAA and cited Tuesday at an NTSB hearing.

"After a duty period of about 10 to 12 hours, the number of observed accidents increased exponentially," NTSB staff member Malcolm Brenner said.

In February, the cockpit crew of a passenger plane operated by Mesa Airlines failed to answer air traffic controllers for 18 minutes, missed the flight's destination in Hawaii and continued for another 15 miles at 21,000 feet over the Pacific Ocean.

The investigation has shown that "both pilots unintentionally fell asleep during cruise flight," NTSB staff member Jena Price said during a presentation to the safety board.

The crew of Go! Flight 1002 eventually answered concerned calls on the radio from ground controllers, turned around and safely landed.

The NTSB report called for analysis of sleep quantity, sleep quality, performance, errors and incidents traced to schedules that disrupt sleep patterns, perhaps while stretching workloads to the maximum allowed.

"They cannot just keep pushing pilots until they drop," said the head of the Air Line Pilots Association, Rory Kay.

He said during a break in the NTSB hearing that "pilot pushing" is an issue.

"We are in tough economic times, we're being asked to do more with less, and we have to support the pilot when he makes the determination that it's time to call it quits," he said.

After reviewing some possible remedies against fatigue in the cockpit, board members unanimously approved the proposal to the FAA, which would be responsible for developing guidance for the airlines to carry out.

The FAA plans to hold a symposium on fatigue management next week with representatives from the aviation industry.

"I want the FAA to have a complete overhaul of the flight time/duty time regulations" that presently allow a 14-hour day with eight hours of flight time, Kay said.